Mazzarri angered by refereeing decisions
Miroslav Klose's goal nine minutes from time condemned Inter to defeat as they slipped to sixth, thanks to Verona's 3-1 win at Udinese.
However, Mazzarri questioned referee Antonio Damato's decision to only book Andre Dias for pulling down Fredy Guarin when through on goal as well his failure to award a penalty when Rolando appeared to be fouled in the area at a set piece.
"Games that are so evenly balanced can also be decided by right or wrong decisions from the match officials, such as the non-sending off of Dias or the clear penalty on Rolando," he told Sky Sport Italia.
"Lazio made the most of their only chance in the second period thanks to a great player like Klose. As for Dias, we were reduced to ten men against Napoli for a similar foul... but let's move on."
The defeat got 2014 off to a bad start for Mazzarri's men after they had finished last year strongly with a 1-0 victory over city rivals Milan.
While he refused to lay all the blame at Damato's door, Mazzarri added this was not the first time he felt his side had been punished by poor officiating.
"I'm not going to blame everything on the refereeing mistakes but this was a match that should have ended as a draw," he added.
"If you ask me whether the referees can influence things with their decisions, then yes, there were two mistakes today. As there have been others in other games."